In the prior art, as proposed by Japanese Application for Registration of Utility Model No. 61-77355 (published under No. 62-189391), a vehicle lift exists which has a slide plate to adjust the length of a vehicle-body support means to support the bottom of a vehicle body at a sufficient surface area for the weight or size of the particular vehicle. Such a vehicle lift is very convenient since it eliminates the necessity of providing a number of vehicle lifts having vehicle-body support means of different lengths for vehicles with different sizes or weights. However, if the slide plate is slidable at all times, it is natural that the slide plate is displaced when a wheel of a vehicle passes thereon. Therefore, it is necessary that the slide plate be unmovable when a wheel of a vehicle passes thereon. Thus so far, in many cases, the slide plate has been bolted manually before a wheel of a vehicle passes thereon. It produces trouble, since the slide plate must be unfixed for the lifting of a next vehicle if the next vehicle requires the adjustment of the length of the vehicle-body support means.